Two helicopters with passengers who were filming a documentary crashed Monday in a remote area of northwest Argentina, killing all 10 people on board both aircrafts, authorities said. The helicopters crashed while flying near Villa Castelli in La Rioja province, about 727 miles (1,170 kilometers) northwest of Buenos Aires, La Rioja Secretary of Security Cesar Angulo told television station TN. "An explosion occurred and it's believed that they must have collided," said Angulo. "Aeronautical experts will have to determine that." Angulo said there were no survivors. He did not release more information on the deceased. Angulo said one of the helicopters belonged to La Rioja province and the other belonged to the neighboring province of Santiago del Estero. He said they were carrying people filming a documentary. After-hours calls to various departments within the municipality of Villi Castelli were not answered.